Wanking over the Drake Equation, again

Oh, this is so silly. It’s a paper titled A Statistical Estimation of the Occurrence of Extraterrestrial Intelligence in the Milky Way Galaxy. All it is is an exercise in modeling the hypothetical distribution of hypothetical intelligent life in the galaxy, taking into account the age distribution of stars.

In the field of Astrobiology, the precise location, prevalence and age of potential
extraterrestrial intelligence (ETI) have not been explicitly explored. Here, we address these
inquiries using an empirical galactic simulation model to analyze the spatial-temporal variations
and the prevalence of potential ETI within the Galaxy. This model estimates the occurrence of ETI,
providing guidance on where to look for intelligent life in the Search for ETI (SETI) with a set of
criteria, including well-established astrophysical properties of the Milky Way. Further, typically
overlooked factors such as the process of abiogenesis, different evolutionary timescales and
potential self-annihilation are incorporated to explore the growth propensity of ETI. We examine
three major parameters: 1) the likelihood rate of abiogenesis (λA); 2) evolutionary timescales (Tevo);
and 3) probability of self-annihilation of complex life (Pann). We found Pann to be the most
influential parameter determining the quantity and age of galactic intelligent life. Our model
simulation also identified a peak location for ETI at an annular region approximately 4 kpc from
the Galactic center around 8 billion years (Gyrs), with complex life decreasing temporally and
spatially from the peak point, asserting a high likelihood of intelligent life in the galactic inner
disk. The simulated age distributions also suggest that most of the intelligent life in our galaxy are
young, thus making observation or detection difficult.

<sigh>. Why? I sympathize with the idea of having fun with math, but the Drake equation is simple-minded algebra, not particularly interesting, and isn’t going to produce testable results.The authors seem to have confused their model with reality. This makes no sense:

We also concluded that at the current time of the study, most intelligent life in the Galaxy is
younger than 0.5 Gyr, with values of probability parameter for self-annihilation between 0 – 0.01;
with a relatively higher value of the annihilation parameter (≥ 0.1), most intelligent life is younger
than 0.01 Gyr. As we cannot assume a low probability of annihilation, it is possible that intelligent
life elsewhere in the Galaxy is still too young to be observed by us. Therefore, our findings can
imply that intelligent life may be common in the Galaxy but is still young, supporting the optimistic
aspect for the practice of SETI. Our results also suggest that our location on Earth is not within the
region where most intelligent life is settled, and SETI practices need to be closer to the inner
Galaxy, preferably at the annulus 4 kpc from the Galactic Center.

But…but…they’re talking about the parameters of their simulation! Their “probability parameter for self-annihilation” is something they set. All of the numbers they plug in are guesstimates, with varying degrees of reasonable justification. Of course they make an optimistic conclusion about SETI! But why should anyone accept their conclusions about an appropriate region for searching for intelligent life? Fudge their parameters a little more and you could shift the zone of likelihood where ever you want. They’ve added nothing to our understanding of the universe, unless you think that multiplying a bunch of numbers by a different bunch of numbers giving you a new result is earthshaking.

I really have to ask…why don’t reviewers simply stamp papers that are all about manipulating the Drake equation with a big red REJECT label? It would save them time and reduce the clutter in the scientific literature. Is there any value in YAWOD (Yet Another Wank Over Drake)? Who finds these informative?


  1. Snarki, child of Loki says

    Number of Intelligent Civilizations in our galaxy?

    I’m hoping we can get to ONE, someday.

    Probably after all the MAGAts die off.

  2. weylguy says

    The Drake equation can be reduced to N > 0, with the sole assumption that the human race can be considered an advanced species, and I can’t imagine why it can be considered as “algebra.”

  3. says

    It’s worth remembering that intelligent life (as we’d recognise it) does not automatically mean technological civilisation. It doesn’t matter how smart you are if your planet is resource poor. Or if your species requires conditions not conducive to developing technology and using technology. Super intelligent seaweed that lives 3 kilometers underwater probably won’t have giant radio transmitters for SETI equipment to hear.

    They do seem to be smart in considering a maximum age for intelligent life. Until a certain point the Universe was probably too dangerous to life for it to evolve, what with all the gamma ray bursts and so on.

  4. birgerjohansson says

    The more we learn about the nuts and bolts of the formation of planetary systems and of individual planets, and of how early life came to be when particular elements were abundant on the surface, and of the many ways climate can get fucked up during a 4.5 billion-year period, the more it looks like the emergence and survival of complex life was a fluke.
    This could give us a high-tech justification for our existence: going across space to repair the many alien biospheres that suffered setbacks, or were destroyed completely by the random vagaries of the universe. As “strong” AI will not be dependent on frail carbon chassi like we are, the thousand-year journey times and hostile conditions will not be the deal-breakers they are for us archaic sapients.
    Until then, we have a duty to look after what is left of biodiversity and stop ruining the world to make the billionaires a bit richer.
    And instead of Soylent Green we should consider the nutritional value of the cleptocracy.

  5. snarkrates says

    Grant Foster over At Tamino’s Open Mind blog refers to such exercises as “mathturbation”. The problem here is that there is no subject matter to study–no empirical evidence. As such, no matter how efficient the use of information, the sum total of the information added to the discussion is zero.

    One of the problems is that we really don’t have a good definition of “intelligence”. Do humans even qualify as “an intelligent life form”? They can be intelligent, certainly, but they are also capable of turning information into negative information.

    It is also interesting to note that AIs have been observed to develop similar pathologies–AIs in the past have developed a potty mouths or started to spout racist garbage. Maybe the key to understanding intelligence is the development of artificial stupidity.

    If we are to understand the possibilities of intelligent life, the only empirical data we have at present are the intelligences in our environment
    1) Human intelligence–such as it is
    2) Other intelligent mammals (e.g. dolphins, apes, elephants…)
    3) Avian intelligence (crows and magpies, mainly)
    4) Artificial intelligence
    At least these subjects offer the possibility of adding to our understanding.

  6. Artor says

    “As we cannot assume a low probability of annihilation…”
    Why can’t they assume that? The self-destructive streak we see in human cultures comes from being tribal primates trying to form cross-tribal communities. A different life form with different ancestry might easily be far more cooperative than we are, and much less likely to experience the problems we do.

  7. microraptor says

    timgueguen @3: Heck, humans haven’t even been transmitting detectable signals into space for a century.

  8. robert79 says

    “In the field of Astrobiology, the precise location, prevalence and age of potential
    extraterrestrial intelligence (ETI) have not been explicitly explored. ”

    I laughed aloud at this first sentence… the authors seem to be completely unaware of a vast corpus of literature (aka, science fiction, and I use that in the broadest sense of the word, including all doodling with Drake’s equation, SETI and astrobiology) which explicitly explores this.

  9. unclefrogy says

    a study that takes the Drake equation and does iterations on all of the known variables might be more interesting then a study that picks one set of variables and assigns them some value by guess work and wishful thinking extrapolated from scant evidence. It has been something of an entertainment on occasion .
    about as useful as estimating how many angles could dance on the head of a pin
    uncle frogy

  10. brucegee1962 says

    My understanding from reading what Drake wrote about it was that he didn’t really intend it to be an actual equation with percentages assigned to all the variables — it was more of a catchy method for organizing an early conference on SETI.

  11. birgerjohansson says

    Toby Tyrell at the University of Southampton made a massive computer simulation published in December. Of 100,000 simulated planets and a 3 billion year simulated period, very few managed to maintain habitable conditions.

  12. slatham says

    What would be interesting is how much any of these models would change with just one other data point. How much would everyone’s idea of how much life there was and how it was distributed change if we had just one other example? I’d find a discussion of that to be of interest and potentially worth exploration in the primary literature.

  13. wsierichs says

    Now tell me Igor, and I won’t be angry. Whose brain did you get for me?

    Abie …

    Abie who?


    Choking sound ensues as Igor is strangled.


    I think the Drake equation speculations are fun if you don’t take them seriously. As of now, we only know of life on one planet.
    As such, it is impossible to calculate the equation because one example is not enough to estimate the odds of life. If we search the solar system and find that, despite favorable conditions (water, biochemicals, heat), no life exists elsewhere, the odds of life in general, much less intelligent life, is pretty small. If we find life at least once somewhere, the odds look better. If we find life all over the place (or in the past on Mars), such as the probable oceans under the surfaces of some moons and Pluto, then I’d say life is pretty much a certainty all over the universe, and intelligent is probable in some places.

    Of course, we first have to find intelligent life on the Earth, and given how we’re slowly, knowingly roasting the environment we require for survival, I think it’s unlikely there is intelligent life here.

  14. John Morales says

    The hypothesis that we are not unique is a good one (principle of mediocrity), but yes, trying to quantify the likelihood via the Drake Equation is pointless, given some parameters remain unquantifiable.

    (or, basically, what weylguy wrote @2)

  15. Nemo says

    It’s hard for me to reconcile “As we cannot assume a low probability of annihilation,” with “optimistic”.

  16. says

    Some of the video signals we’ve sent into space were “Gilligan’s Island”. If ET received that and could even translate it, then would they consider it the output of an intelligent species? Even if they instead got Star Trek TOS, one of those shows was “Spock’s Brain”. Brain, brain, what is brain?

    Sagan pointed out that the first video signal we broadcast was the opening of the 1936 Olympics, starring Hitler.

    Given the radio evidence from this planet, and the lack of radio evidence from any other planet, I deduce that you cannot prove that there is any intelligent life anywhere in the universe, including planet Earth. To say otherwise would be unscientific.

  17. says

    #5: Octopi and cuttlefish are smart molluscs.

    #15: those simulations did not take into account Gaia-type planet-scale adaptation. I say that the faint-young-sun paradox suggests that such adaptation happened here.

    I even speculate that the 5 mass extinctions before the present ongoing one suggests that there were 5 technological civilizations on this planet before us. Like us, they messed things up; then (like us, I hope) they cleaned up their act and re-optimized the biosphere before going extinct or regressing. (What business has a mollusc being as smart as a cuttlefish? And what use has a water-bear for resistance to vacuum and radiation?)

  18. says

    You go, PZ! Beat that dead horse! Because, if you hadn’t brought this paper to our attention, how many of us would have heard about it? I mean, regular readers of this blog would already know how facile the Drake Equation is, but of course you must reiterate that lesson again and again instead of letting the issue fade into relative obscurity! Wouldn’t it be a plot twist if someone new to the blog misunderstood your argument and started admiring the Drake Equation? Zounds!

  19. DanDare says

    There is subject matter to study. Life on Earth and the distribution of stars, planets and materials.
    The probability of life on an Earth like planet evolving to at least radio tech without dying out is > 0 since here we are.
    Does the equation have any utility or predictive power? I guess it can set an upper bound on our expectations.

  20. call me mark says

    The Drake equation is just a fancy way of saying “I don’t know” – which is, I suppose, appropriate in the face of a lack of information.

    You can plug some reasonable suppositions into it and get N=10000
    You can plug other reasonable suppositions into it and get N=1

    Really useful.

  21. unclefrogy says

    in case you had not noticed the Drake equation which is not a new thing by any means is not fading away.
    hence ……………..
    uncle frogy

  22. snarkrates says

    Dan Dare: “There is subject matter to study.”

    Bullshit. The Drake Equation is phrased in terms of probabilities. The only thing you can say about a probability of an event by observing a single event is that the probability is nonzero.

    It is not a Bayesian analysis because there is no update of prior probabilities based on data–for the simple reason that there is no data.

    Even the terms used in the equation are arbitrary–hell, it’s not even clear Earth would qualify as an example of a planet where life evolved.

    The sole value of the Drake equation is that it demonstrates the value of scientific inquiry over unguided speculation.

  23. leerudolph says

    @21: “I even speculate that the 5 mass extinctions before the present ongoing one suggests that there were 5 technological civilizations on this planet before us. Like us, they messed things up”

    An old friend’s older USENET .sig (this one from 1995, but I’m sure it was out there at least 5 years earlier):

    Derek Tearne. -- derek@fujitsu.co.nz -- Fujitsu New Zealand --
    Some of the more environmentally aware dinosaurs were worried about the
    consequences of an accident with the new Iridium enriched fusion reactor.

    "If it goes off only the cockroaches and mammals will survive..." they said.

  24. PaulBC says

    RobG@29 Considering Carl Sagan covered the Drake equation in an episode of Cosmos. is any of this really separable? I agree that Sagan paid particular attention to the likelihood that intelligent life destroys itself, but that’s implicit in the Drake equation and a possible explanation for the “Fermi paradox.”

    I agree with PZ that the Drake equation in itself isn’t very interesting, just a product of independent probabilities that can’t really be measured. I guess it gives some ballpark estimates.

    Personally, I always thought too little attention was given to the possibility that the expected frequency of intelligent life is much less than 1 per galaxy (but non-zero obviously). It fits with the fact that we exist and we don’t observe anyone else. On the other hand, I would far prefer it to be a lot greater than that. Either we find evidence or we don’t, and the rest is pure speculation.

  25. PaulBC says

    Calling it an “equation” is also kind of silly. It’s a formula. You fill in the parameters and calculate a value. While you could work out “the average number of planets that can potentially support life per star that has planets” given N “the number of civilizations in our galaxy with which communication might be possible” I can’t conceive of a real situation where anyone wants to do this.

    And yes, technically, it’s an equation, but really not a very interesting one at all. Equations are interesting when you solve for an unknown, not when you just plug and chug.

  26. KG says

    about as useful as estimating how many [angels] could dance on the head of a pin – unclefrogy@10

    The question the medieval philosophers were getting at was: is the number finite? (They didn’t have the mathematical notion of infinity quite as we do, but that was the gist.) IOW, since angels could be whatever size they chose, is space indefinitely divisible or not – a question that is still unanswered.

  27. KG says

    one example is not enough to estimate the odds of life. – wsierichs@17

    But the timescale and trajectory of life on earth gives some clues. Life itself got going on earth pretty quickly (in geological terms), but technological culture took several billion years, and we’re probably nearer the end of the earth’s habitable era than the beginning. My guess is that microbial-type life is fairly common, but technological culture very rare.

  28. Rob Grigjanis says

    PaulBC @30:

    Considering Carl Sagan covered the Drake equation in an episode of Cosmos. is any of this really separable?

    Fermi’s death (1954) and the Drake equation (1961) are certainly separable.

    Personally, I just feel sorry for Frank Drake.

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